Polymaleates are commonly used as water treatment agents, dispersing agents, and chelating agents in applications where color of the polymer is not critical. Since polymaleates generally appear dark brown in color, such polymers are inappropriate for many detergent and textile applications where low color is desirable. This is especially true where the polymer is to be applied to a textile, for example, as a durable press resin where a high color polymer may cause undesired color formation on the textile.
There are many processes for preparing polymaleates and copolymers thereof, for example, such processes are disclosed in U.S. Pat. Nos. 5,135,677; 5,064,563; 4,519,920; 4,555,557; 4,668,735; 4,589,995; and 4,659,793 wherein the polymaleates are prepared in an organic solvent or water. Unfortunately, these processes yield polymaleates which appear dark in color as evidenced by Gardner color number of greater than 8.
U.S. Pat. No. 4,709,091 describes a process for preparing polymaleic acid which involves neutralizing maleic acid in an aqueous medium with an alkali metal hydroxide or ammonia, polymerizing the maleic acid in the presence of an initiator, and adding a further amount of the alkali metal hydroxide or ammonia. U.S. Pat. No. 4,709,091 suggests that sulfonate comonomers may be used along with the maleic acid. The polymalic acid polymers, however, appear dark in color as evidenced by Gardner color number of greater than 8.